genfct.c

详细的OFDM设计过程

/*--------------Global Functions------------
			for transmitter and receiver
			
			Vinod Patmanathan
			Black Team
	
--------------------------------------------*/

#include "C:/ti/c6000/dsplib/include/dspf_sp_maxval.h"
#include "C:/ti/c6000/dsplib/include/dspf_sp_minval.h"
#define MAX(a,b) ((a) > (b) ? (a):(b))

// getbits: Get n bits from position p
unsigned int getbits(unsigned int x, int p, int n)
{
	// It takes the n bits from position p, (first bits is p=0), and downwards. 
	// getbits(b1010001111, 5, 4) gives 3, 0011
	return (x >> (p+1-n)) & ~(~0 << n);
}

//returns the # of ones in an int variable
int weight(unsigned int x)
{
	int i;
	int w = 0;
	for(i=0; i<8*sizeof(x); i++)
		w += getbits(x,i,1);

	return w;
}

void setbuffer(short *output, short *input, int lenin)
{
	int i;
	
	for(i=0; i<lenin; i++){
		output[2*i] = input[i];
		output[(2*i)+1] = 0;
	}
	
} 

// output: output buffer, sinetable: pointer to a sinetable, len: length of sinetable
void assemble_first(short *output, short *sinetable, short *training,
					 int lensin, int lentra)
{
	int i;
	for(i=0; i<lensin ; i++){
		output[2206+(2*i)] = sinetable[i];
		output[2206+(2*i)+1] = 0;
	}
	
	for(i=0;i<lentra;i++){
		output[(2208+(2*lensin))+(2*i)] = training[i];
		output[(2208+(2*lensin))+(2*i)+1] = 0;
	}
	
}

short total_bits(const short *input, int len){
	
	short sumbits;
	int i;
	sumbits = 0;
	for(i=0; i<len; i++){
		sumbits += input[i];
	}
	
	return sumbits;
} 


void sine_sync(short *output, short *sinetable, int lensin, int buffsize)
{
	int i;
	for(i=0; i<lensin ; i++){
		output[(buffsize-(2*lensin))+(2*i)] = sinetable[i];
		output[(buffsize-(2*lensin))+(2*i)+1] = 0;
	}
			
}


void interleavebuffer(short *output, float *input, int lenin)
{
	int i;
	
	for(i=0; i<lenin; i++){
		output[2*i] = (short)(32767*input[i]);
		output[(2*i)+1] = (short)(-32767*input[i]);
	}
	
} 

void interleavebuffer2(short *output, float *input, int lenin)
{
	int i;
	float max;
	float min_abs = _fabsf(DSPF_sp_minval(input, lenin));
	float max_abs = _fabsf(DSPF_sp_maxval(input, lenin));
	
	
	max = _rcpsp(MAX(max_abs,min_abs));
					
	for(i=0; i<lenin; i++){
		output[2*i] = (short)(5000*(input[i])); //5000: default
		output[(2*i)+1] = (short)(-5000*(input[i])*max);
	}
	
} 

short detection(float *rxbuffer,int threshold, int size) {

	short i;
	for(i=0; i<size;i++) {
		if (_fabsf(rxbuffer[i])> threshold){
		return i;
		}
	}
	
	return 0;
}

void deinterleavebuffer(short *output, short *input, int lenout)
{
	int i;
	for(i=0; i<lenout; i++)
		output[i] = input[2*i];
}